開水路粗度急変部における流れの遷移と流砂機構に関する研究

点击翻译按钮获取中文摘要

1. Experiments of local scour in downstream reaches of various types of bed protection works including smooth fixed bed were carried out under dynamical equilibrium conditions of bed load. Variations of scour holes profiles and their maximum depths with time were discussed on three types of bed protection works, and compared with those under a static equilibrium condition. Flow characteristics, such as, velocity distributions, bed shear stress and pressure on the scoured bed were also measured at several stages of scour process. The scour processes could be simulated by the case of bed shear stress distributions measured along the maximum scour profile and non-equilibrium bed load functions, especially in the early stage of the scour.2. Field measurement of scour profiles were carried out at a downstream reach of hollow-squared blocks in the Manganji River in Hyogo prefecture, and the observed scour profiles and velocity distributions proved to be similar to those measured in the experiments.3. Water surface profiles and turbulent structures of open channel flows produced by sudden change in side-wall roughness from smooth to rough were discussed experimentally. The transition of flow was found to mainly depend on the bed slope and classified into three patterns. In the downstream reach after the roughness change, distributions of the velocity and turbulence property vary with development of the internal boundary layer similar to those by sudden change in bottom roughness.